Hair clippers

ABSTRACT

A hair clipper, particularly for incorporation in a battery powered electric dry shaver, comprising first and second mutually slidingly reciprocable and inherently slightly resilient toothed cutters resiliently urged to assume a similar curvature to one another along the direction of reciprocation to tend to render uniform the pressure distribution therebetween.

BACKGROUND OF THE INVENTION

This invention relates to hair clippers. Hair clippers may beincorporated in other appliances such as ac or battery powered electricdry shavers, where they are sometimes referred to as long hair trimmers,or may be separate appliances.

FIELD OF THE INVENTION

In certain presently available electric dry shavers a long hair trimmeris provided comprising first and second mutually slidingly reciprocabletoothed cutters. Both cutters are rectilinear, one being fixed and theother movable, and the movable cutter is urged against the fixed cutterby means of a number of coil springs. Both cutters are substantiallyrigid but there is a size, weight and power consumption limit to therigidity that can be given to the cutters. Consequently it has beenfound that the cutters can bow to some extent, and thus to achieve aneffective cutting action at points between the springs, the force of thesprings has to be increased such that the cutters are pressed togetherto a greater extent than necessary in the neighbourhood of the springs.The efficiency is thereby reduced and the power consumption increased.

An object of the invention is to provide a hair clipper of improvedefficiency consistent with an effective clipping action.

SUMMARY OF THE INVENTION

According to the present invention there is provided a hair clippercomprising first and second mutually slidingly reciprocable andinherently slightly resilient toothed cutters resiliently urged toassume a similar curvature to one another along the direction ofreciprocation to tend to render uniform the pressure distributiontherebetween.

More particularly, the invention provides a hair clipper comprisingfirst and second toothed cutters adapted to be driven in relativesliding reciprocation to effect a cutting action, wherein both cuttersare inherently slightly resilient, wherein resilient means acts on thefirst cutter to urge it against the second cutter, wherein reactionmeans acts on the second cutter to oppose the force due to saidresilient means, and wherein said resilient means and said reactionmeans provide a force couple that imparts a similar curvature to bothcutters along the direction of reciprocation, whereby to tend to renderuniform the pressure distribution between the two urged togethercutters.

The resilient means may comprise at least one spring acting on the firstcutter intermediate its ends, and the reaction means may includesubstantially non-resilient reaction structure acting on each endportion of the second cutter.

In one embodiment the first cutter is adapted to be driven in slidingreciprocation, and means is provided to locate the second cutter inposition longitudinally and laterally while permitting it to curveresiliently to assume a similar curvature to the first cutter. Saidlocating means may include at least one piston working in a bore in theshaver body and urged into engagement with the second cutter to actthereon away from the first cutter and against said reaction means. Saidpiston may pass through a slot in the first cutter and thus also serveto locate the first cutter laterally and to guide the first cutter inits longitudinal reciprocation.

In another embodiment, the substantially non-resilient reactionstructure comprises a pair of pins near opposite ends of the secondcutter, the pins also serving to locate the second cutter longitudinallyand laterally, and furthermore to locate the first cutter laterally andto guide it in its longitudinal reciprocation.

The result of tending to render uniform the pressure distributionbetween the cutters is to provide an effective or improved cuttingaction with greater efficiency and thus at reduced power consumption.With an effective cutting action the comfort of the user is enhanced andhair pulling during clipping is minimized. In a battery powered electricdry shaver it is important that the power consumption of the clipper isas low as possible consistent with an effective cutting action. When aclipper is driven by an AC reluctance motor the amplitude of clipperreciprocation decreases if the mechanical power consumed by the clippingaction increases, thus decreasing the effectiveness of the cuttingaction, and therefore again it is important to increase the clipperefficiency.

BRIEF DESCRIPTION OF DRAWINGS

An embodiment of the invention will now be described, by way of example,with reference to the accompanying drawings, in which:

FIG. 1 is a longitudinal section, partly broken away, through a hairclipper according to the invention;

FIG. 2 is a scrap section on an enlarged scale on line 2--2 of FIG. 1;

FIGS. 3A and 3B are a top plan and an end view respectively of themovable cutter of the clipper;

FIGS. 4A and 4B are a top plan and an end view respectively of the fixedcutter of the clipper;

FIG. 5 is a longitudinal section, partially broken away, through asecond embodiment of a hair clipper according to the invention; and

FIG. 6 is a section on line A--A of FIG. 5.

DESCRIPTION OF PREFERRED EMBODIMENT

Referring to the drawings there is shown a hair clipper, sometimesreferred to as a long hair trimmer, incorporated in a AC or batterypowered electric dry shaver, a portion of the body of the shaver beingshown at 10. The clipper comprises a first elongate movable toothedcutter 11 and a second substantially fixed elongate toothed cutter 12.The first cutter 11 is adapted to be driven in sliding longitudinalreciprocation relative to the second cutter 12 to effect a cuttingaction. To this end the rear edge of the cutter 11 is provided with anobliquely bent tab 13 provided with a notch 14. In use a reciprocatingelement of the shaver drive mechanism is engaged in the notch 14 toreciprocate the cutter 11. Such drive mechanism is not shown but anumber of suitable mechanisms are currently available in the dry shaverart. The drive mechanism would normally be under control of a switch forselective operation of the clipper when required.

The area of mutual sliding contact between the two cutters in use isshown on cutter blade 11 as the longitudinal forward toothed stripportion 18 and the two longitudinally spaced strip portions 19, 20 atthe rear edge of cutter 11, as shown in FIGS. 3A and 3B.

The cutters are each inherently slightly resilient along their length. Anumber of metals are suitable for forming cutter teeth and most of suchmetals would also exhibit sufficient inherent resilience for the purposeof this invention, thereby permitting the teeth to be integrally formedalong the forward edges of the respective cutters. A preferred materialis a stainless tempered steel.

The first, movable cutter 11 is resiliently urged against the secondcutter by resilient means in the form of two spaced coil springs 15received in frusto-conical recesses 16 in the body 10 of the shaver.During reciprocation the springs 15 can tilt from side to side in theirrecesses 16 to follow the cutter reciprocation. The springs 15 act oncutter 11 substantially midway between the centre of the length of thecutter 11 and its end. The cutter 11 is located laterally and guided inits longitudinal reciprocation by means of two pistons 28, to bedescribed below, extending through slots 17 formed near the end portionsof the cutter 11.

The second, fixed cutter 12 has set-back end portions 22 trapped beneathflanges 23 formed on the body 10 of the shaver. Two spaced coil springs24 are received in respective bores 25 in the body 10. The springs 24act on the respective pistons 28 which work in and extend partially fromthe bores 25. The outward ends of the pistons 28 are provided with studs26 fitted into bores 27 through the second cutter 12. The pistons 28 andsprings 24 are located between the springs 15 and the end portions 22 ofthe second cutter 12. The pistons 28 thus urge the end portions 22against the flanges 23, to locate the second fixed cutter 12 in positionlongitudinally and laterally, while permitting the cutter 12 to curvebetween its ends to assume a similar curvature to the first cutter 11,as imposed by the first cutter 11 under the action of the springs 15.

It will be appreciated that the flanges 23 serve as substantiallynon-resilient reaction structure opposing the major action of the twosprings 15 and the minor action of the two springs 24. In FIG. 1, theleft-hand structure 23 and spring 15 form a first force couple and theright-hand structure 23 and spring 15 form a second force couple, bothcouples acting similarly to resiliently urge the cutters to assume asimilar upward curvature to one another along the direction ofreciprocation.

It is found that the action of the couples in causing the cutters toassume a similar curvature to one another together with the inherentslight resilience of the cutters themselves tends to render uniform thepressure distribution between the two urged together cutters. Thepressure distribution is found to be more nearly uniform than in thecase of two substantially rigid rectilinear cutters. In consequence thetotal force between the cutters can be reduced, the cutting actionefficiency is improved, and the power consumption considerably reduced.For example in one embodiment the total force between the cutters was300 grams.

The clipper in the embodiment of FIGS. 1 to 4 may also be readily andquickly assembled. The springs and pistons are dropped in theirrecesses, the movable blade 11 located over the pistons, and the endportions 22 of the fixed blade 12 are then slid beneath the flanges 23,perpendicular to the plane of FIG. 1, until the studs 26 enter into thebores 27.

Referring now to FIGS. 5 and 6 there is shown a second embodiment of theinvention. The following structure is similar to correspondinglyreferenced structure in FIGS. 1 to 4: the shaver body 10, the firstmovable cutter 11, the second fixed cutter 12, drive tap 13, coilsprings 15, frusto-conical recesses 16, slots 17 in cutter 11, and stripportions 18 and 20 of cutter 11 that slide in engagement with cutter 12.As shown in FIG. 5, three spaced coil springs in three recesses 16 areprovided resiliently to urge the first movable cutter 11 against thesecond fixed cutter 12, in place of the two coil springs of FIG. 1.

In this embodiment the reaction structure opposing the action of thethree springs 15 comprises a pair of pins 29 and flat spring clips 40,the pins 29 also serving to locate the second fixed cutterlongitudinally and laterally, and to guide the first cutter in itslongitudinal reciprocation. The pins 29 are disposed near opposite endsof the cutter 12. Each pin has a shank having a central portion 30ground to be a press fit in a bore 31 in the shaver body 10. The shankhas an enlarged diameter upper portion 32 providing a shoulder 33 seatedagainst the shaver body 10. Each pin has a head 34 and a neck 35 betweenthe head and the portion 32. The spring clips 40 clip on the neck 35.The clips 40 are shaped part-rings and, being inherently resilient, canaccommodate the blade curvature as seen in FIG. 5.

The pin portions 32 extend through the slots 17 of the first blade, tolocate the first blade laterally and to guide it in its longitudinalreciprocation, and also extend through apertures through the endportions of the second blade 12. The left-hand aperture 36 in FIG. 5 iscircular and locates the blade 12 longitudinally and laterally on theportion 32 of the pin 29. The right-hand aperture 37 in FIG. 5 isslightly elongate in the direction of the blade 12 to accommodate theupward resilient curvature of the blades. The aperture 37 also locatesthe blade 12 laterally on portion 32 of the pin 29.

Referring again to FIGS. 4 and 5, it will be appreciated that there isinevitably a small increase of pressure between the two cutters in theneighbourhood of the springs 15. This pressure increase is relativelyvery small as compared with the prior art case of two rectilinearcutters, as explained above. In a further modification even this verysmall pressure increase can be reduced by appropriate shaping of thecutters.

I claim:
 1. A hair clipper comprising first and second elongate toothedcutters, said first cutter being adapted to be driven in slidingreciprocation, means for driving said cutters in mutual slidinglongitudinal reciprocation to effect a hair clipping operation, bothsaid cutters being inherently slightly resilient along their length,means for locating said second cutter in position longitudinally andlaterally while permitting said second cutter to curve resiliently toassume a similar curvature to said first cutter, resilient means andreaction means, said resilient means acting on the first cutter to urgethe first cutter against the second cutter, said reaction means actingon the second cutter to oppose the force due to said resilient means,said clipper having a body member provided with a bore, said locatingmeans includes at least one piston, said piston working in said bore,and means urging said piston into engagement with said second cutter toact thereon away from said first cutter and against said reaction means,said resilient means and said reaction means providing a force couplethat imparts a similar curvature to both said cutters along thedirection of reciprocation, whereby to tend to render uniform thepressure distribution between the two urged together cutters.
 2. A hairclipper according to claim 1 wherein said first cutter is provided witha slot extending lengthwise of said first cutter, and wherein saidpiston passes through said slot, whereby said piston also serves tolocate the first cutter laterally and to guide the first cutter in itslongitudinal reciprocation.
 3. A hair clipper according to claim 1wherein said reaction structure comprises a pair of pins, said pinsdisposed near opposite ends of the second cutter, said pins also servingas said locating means to locate the second cutter in positionlongitudinally and laterally, and said pins further serving to locatethe first cutter laterally and to guide it in its longitudinalreciprocation.
 4. A hair clipper according to claim 1 wherein the totalforce between said cutters is substantially 300 grams.
 5. A hair clipperaccording to claim 1 wherein said resilient means comprises at least onespring, said at least one spring acting on the first cutter intermediatethe ends of said first cutter, and wherein the reaction means includessubstantially non-resilient reaction structure acting on each endportion of the second cutter.
 6. A hair clipper according to claim 5including at least two said springs acting in substantially the samedirection and spaced apart from one another, said reaction means actingin substantially the opposite direction, whereby said curvature is inone sense from end to end of the cutters.